The art, or science of cultivating plants, whether for pleasure or profit, requires the application to plants of chemicals or biocides e.g., fertilizers, insecticides, herbicides, and the like often in the form of liquids, or liquid solutions. Certain favored plants, e.g., must be protected from competition with other plants, i.e. weeds. Weeds are destroyed to make room for the cultivated plants.
In modern gardening, herbicides as liquids or liquid solutions are often applied to weeds. In such applications it is desirable, and often essential to apply the liquid only upon the weeds while minimizing or avoiding contact between the liquid and the cultivated plants. Some few herbicides are selective, killing certain types of weeds, while leaving the cultivated plants unharmed. Other herbicides however are less selective, or lacking in selectivity. Some herbicides thus damage, or injure the cultivated plants as well as the weeds, and some may even kill every plant with whose leaves they come into contact. It is thus desirable to control the applications of the herbicides, or weed killers, to prevent waste, if indeed it is not desirable, or even essential to prevent injury, or destruction of the cultivated plants.
Apparatus, or machinery, for spraying plants of various types are well known. A large class of such apparatus is that used for spraying orchards, or that used by large agricultural establishments, these taking the form of relatively large, complex pieces of equipment. Such equipment, as described e.g. in U.S. Pat. No. 3,216,664 and U.S. Pat. No. 3,227,376, generally includes a wheeled vehicle which carries a tank of the material to be dispersed, a large fan or blower to create a large volume, high velocity air blast, a self-contained power plant, and pump for pumping the liquid from the tank into the air stream for dispersement. Smaller, far less complex portable sprayers have also been designed and carried on the backs of or been towed by individual operatives; and small applicators with liquid fillable tanks have also been mounted on wheels, and thereby been made transportable for use by individual operatives.
In U.S. Pat. No. 3,267,610 there is described an applicator for applying a liquid spray to the ground at the base of a tree. The applicator is constituted of a liquid fillable tank, and a movable applicator inclusive of an elongated handle, movable applicator head, and shield. The movable applicator is connected to a tank via a long flexible hose. A major difficulty with this apparatus, inter alia, is that the operative must carry the movable applicator portion while using same, and it is tethered via the flexible hose to the tank, and the hose must be dragged about while the tank is rested upon the ground in a spotted location.
Applicators wherein a tank has been mounted on a wheeled carriage are described in U.S. Pat. No. 2,740,664 and U.S. Pat. No. 2,581,678. These applicators, albeit they can be propelled by an operative nonetheless suffer certain deficiencies not the least of which is related to their undue complexity, lack of mobility and low selectivity in targeting the plants and shrubs on which liquid is to be applied.